Declaration of function and use it

[gauravsharma0190]

@mrjj
it is defined as

///ontrack.h///

#ifndef __ONTRACK_h
#define __ONTRACK_h
void cannyThresold(int,void*);
#endif
......

///ontrack.cpp
#include "ontrack.h"
#include<opencv2/opencv.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/core/core.hpp>
void CannyThreshold(int, void*)
{
/// Reduce noise with a kernel 3x3
blur( src_gray, detected_edges, Size(3,3) );
/// Canny detector
Canny( detected_edges, detected_edges, lowThreshold, lowThreshold*ratio, kernel_size );

/// Using Canny's output as a mask, we display our result
dst = Scalar::all(0);

src.copyTo( dst, detected_edges);
imshow( window_name, dst );
}

.....
thus i include ontrack.h in mainwindow.cpp code.
but error occurs.
Why??
i can't understand.

[mrjj]

I dont understand either.
Seems fine.
try to define a test function
as in
ontrack.h
void mytest();
and call that from main.

If that is still not known, it means that mainwinow do not really include ontrack.h for some reason.

[jsulm]

@gauravsharma0190 You call it like this CannyThreshold(0, 0); and in ontrack.cpp it is defined like void CannyThreshold(int, void*). But in ontrack.h it is void cannyThresold(int,void*); please fix the name of the function.

[mrjj]

@jsulm
heh Good spotted. completely missed "old" :)

[gauravsharma0190]

@mrjj
I fix canny as Canny in .h file
but again error occurs.

[gauravsharma0190]

@jsulm
Hey i fixed it .But again error.

[jsulm]

@gauravsharma0190 "But again error" - why don't you say what error you get now?

[gauravsharma0190]

@jsulm
yes it tells undefined reference to 'CannyThresold(int,void*)'.
collect2:error ld returned 1 exit status.

[jsulm]

@gauravsharma0190 Is ontrack.cpp part of your project and is it built?
"undefined reference to 'CannyThresold(int,void*)" - means linker cannot find CannyThresold(int,void*)

[gauravsharma0190]

@jsulm
Actually i put .h and .cpp file in my qt project folder.

[jsulm]

@gauravsharma0190 But did you add them to your project?
They should be in the PRO file, like:

SOURCES += main.cpp\
        mainwindow.cpp\
        ontrack.cpp

HEADERS  += mainwindow.h\
        ontrack.h

[gauravsharma0190]

@jsulm
i added it but gives error as
parse error onTrack.cpp
Makefile error 3

[jsulm]

@gauravsharma0190 After changing PRO file you need to rerun qmake (right-click on the project in QtCreator and then "Run qmake". Then do a rebuild.

[gauravsharma0190]

@jsulm
I done it
Now gives many error regarding onTrack.cpp file.

[jsulm]

@gauravsharma0190 Well, I guess you have many issues there...

[gauravsharma0190]

@jsulm
Yeap.
are they function's issuses or anything.
I can't undersatnd everything is all right so Why all these issuses are there.
I will send you these issue.

[gauravsharma0190]

@gauravsharma0190
Here are all the errors
...

/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:9: error: 'blur' was not declared in this scope
     blur(gray, edge, Size(3,3));
                               ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:6: error: 'Mat' does not name a type
 Mat image, gray, edge, cedge;
 ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:7: error: 'void CannyThreshold(int, void*)' was declared 'extern' and later 'static' [-fpermissive]
   static void CannyThreshold(int, void*)
                                        ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:-1: In function 'void CannyThreshold(int, void*)':

/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:9: error: 'edge' was not declared in this scope
     blur(gray, edge, Size(3,3));
                ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:9: error: 'edge' was not declared in this scope
     blur(gray, edge, Size(3,3));
                ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:9: error: 'blur' was not declared in this scope
     blur(gray, edge, Size(3,3));
                               ^

/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:12: error: 'Canny' was not declared in this scope
     Canny(edge, edge, edgeThresh, edgeThresh*3, 3);
                                                  ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:13: error: 'cedge' was not declared in this scope
     cedge = Scalar::all(0);
     ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:15: error: 'src' was not declared in this scope
     src.copyTo(cedge, edge);
     ^
/home/pi/Desktop/qt/Desktop1/onTrackBall.cpp:16: error: 'imshow' was not declared in this scope
     imshow("Edge map", cedge);
                             ^
/usr/local/include/opencv2/highgui/highgui.hpp:78: note:   'cv::imshow'
 CV_EXPORTS_W void imshow(const string& winname, InputArray mat);

[gauravsharma0190]

This post is deleted!

[gauravsharma0190]

@jsulm
Hey i have posted the error
i can't undersatnd why i am getting these error.
everything is all right.

[jsulm]

@gauravsharma0190 Nothing is all right with this code.
"was not declared in this scope" - you have to check where are those declared or why they are not declared (blur, edge, Mat,...). For example:

cedge = Scalar::all(0);

where is cedge declared? You're trying to access a variable which was not declared.

This one says that you first declared the function extern and later static. Why? Since it is just a function it neither has to be static nor extern!

error: 'void CannyThreshold(int, void*)' was declared 'extern' and later 'static' [-fpermissive]
   static void CannyThreshold(int, void*)

You really have to fix your code! And I really don't understand why you think your code is OK although there are really basic issues (not related to Qt at all)!